diff --git a/mod/display.php b/mod/display.php
index 21e28d5617..047f752c98 100644
--- a/mod/display.php
+++ b/mod/display.php
@@ -77,7 +77,7 @@ function display_init(App $a)
 		displayShowFeed($item["id"], false);
 	}
 
-	if (stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/activity+json')) {
+	if (ActivityPub::isRequest()) {
 		$wall_item = Item::selectFirst(['id', 'uid'], ['guid' => $item['guid'], 'wall' => true]);
 		if ($wall_item['uid'] == 180) {
 			$data = ActivityPub::createActivityFromItem($wall_item['id']);
diff --git a/mod/profile.php b/mod/profile.php
index fd23964e41..a284e10f2d 100644
--- a/mod/profile.php
+++ b/mod/profile.php
@@ -50,7 +50,7 @@ function profile_init(App $a)
 		DFRN::autoRedir($a, $which);
 	}
 
-	if (stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/activity+json')) {
+	if (ActivityPub::isRequest()) {
 		$user = DBA::selectFirst('user', ['uid'], ['nickname' => $which]);
 		if ($user['uid'] == 180) {
 			$data = ActivityPub::profile($user['uid']);
diff --git a/src/Module/Inbox.php b/src/Module/Inbox.php
index d47419a415..21dd77151c 100644
--- a/src/Module/Inbox.php
+++ b/src/Module/Inbox.php
@@ -47,6 +47,6 @@ class Inbox extends BaseModule
 
 		ActivityPub::processInbox($postdata, $_SERVER, $uid);
 
-		System::httpExit(202);
+		System::httpExit(201);
 	}
 }
diff --git a/src/Protocol/ActivityPub.php b/src/Protocol/ActivityPub.php
index ad27535ae6..5b5d16e85a 100644
--- a/src/Protocol/ActivityPub.php
+++ b/src/Protocol/ActivityPub.php
@@ -55,6 +55,12 @@ class ActivityPub
 {
 	const PUBLIC = 'https://www.w3.org/ns/activitystreams#Public';
 
+	public static function isRequest()
+	{
+		return stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/activity+json') ||
+			stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/ld+json');
+	}
+
 	public static function transmit($data, $target, $uid)
 	{
 		$owner = User::getOwnerDataById($uid);
@@ -66,19 +72,19 @@ class ActivityPub
 		$content = json_encode($data);
 
 		// Header data that is about to be signed.
-		/// @todo Add "digest"
 		$host = parse_url($target, PHP_URL_HOST);
 		$path = parse_url($target, PHP_URL_PATH);
-		$date = date('r');
+		$digest = 'SHA-256=' . base64_encode(hash('sha256', $content, true));
 		$content_length = strlen($content);
 
-		$headers = ['Host: ' . $host, 'Date: ' . $date, 'Content-Length: ' . $content_length];
+		$headers = ['Content-Length: ' . $content_length, 'Digest: ' . $digest, 'Host: ' . $host];
 
-		$signed_data = "(request-target): post " . $path . "\nhost: " . $host . "\ndate: " . $date . "\ncontent-length: " . $content_length;
+		$signed_data = "(request-target): post " . $path . "\ncontent-length: " . $content_length . "\ndigest: " . $digest . "\nhost: " . $host;
 
 		$signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 
-		$headers[] = 'Signature: keyId="' . $owner['url'] . '#main-key' . '",headers="(request-target) host date content-length",signature="' . $signature . '"';
+		$headers[] = 'Signature: keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) content-length digest host",signature="' . $signature . '"';
+
 		$headers[] = 'Content-Type: application/activity+json';
 
 		Network::post($target, $content, $headers);
@@ -157,7 +163,7 @@ class ActivityPub
 			'toot' => 'http://joinmastodon.org/ns#']]];
 
 		$data['type'] = 'Create';
-		$data['id'] = $item['uri'];
+		$data['id'] = $item['uri'] . '/activity';
 		$data['actor'] = $item['author-link'];
 		$data['to'] = 'https://www.w3.org/ns/activitystreams#Public';
 		$data['object'] = self::createNote($item);
@@ -210,7 +216,8 @@ class ActivityPub
 			'id' => System::baseUrl() . '/activity/' . System::createGUID(),
 			'type' => $activity,
 			'actor' => $owner['url'],
-			'object' => $profile['url']];
+			'object' => $profile['url'],
+			'to' => $profile['url']];
 
 		logger('Sending activity ' . $activity . ' to ' . $target . ' for user ' . $uid, LOGGER_DEBUG);
 		return self::transmit($data,  $profile['notify'], $uid);
@@ -227,7 +234,8 @@ class ActivityPub
 			'actor' => $owner['url'],
 			'object' => ['id' => $id, 'type' => 'Follow',
 				'actor' => $profile['url'],
-				'object' => $owner['url']]];
+				'object' => $owner['url']],
+			'to' => $profile['url']];
 
 		logger('Sending accept to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
 		return self::transmit($data,  $profile['notify'], $uid);
@@ -244,7 +252,8 @@ class ActivityPub
 			'actor' => $owner['url'],
 			'object' => ['id' => $id, 'type' => 'Follow',
 				'actor' => $profile['url'],
-				'object' => $owner['url']]];
+				'object' => $owner['url']],
+			'to' => $profile['url']];
 
 		logger('Sending reject to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
 		return self::transmit($data,  $profile['notify'], $uid);
@@ -263,7 +272,8 @@ class ActivityPub
 			'actor' => $owner['url'],
 			'object' => ['id' => $id, 'type' => 'Follow',
 				'actor' => $owner['url'],
-				'object' => $profile['url']]];
+				'object' => $profile['url']],
+			'to' => $profile['url']];
 
 		logger('Sending undo to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
 		return self::transmit($data,  $profile['notify'], $uid);
@@ -277,7 +287,7 @@ class ActivityPub
 	 */
 	public static function fetchContent($url)
 	{
-		$ret = Network::curl($url, false, $redirects, ['accept_content' => 'application/activity+json']);
+		$ret = Network::curl($url, false, $redirects, ['accept_content' => 'application/activity+json, application/ld+json']);
 		if (!$ret['success'] || empty($ret['body'])) {
 			return;
 		}
diff --git a/src/Worker/Delivery.php b/src/Worker/Delivery.php
index ef3a34649d..8ee00af630 100644
--- a/src/Worker/Delivery.php
+++ b/src/Worker/Delivery.php
@@ -440,24 +440,21 @@ q	 *
 			// send comments and likes to owner to relay
 			logger('ActivityPub followup: ' . $loc);
 			$data = ActivityPub::createActivityFromItem($target_item['id']);
-			$content = json_encode($data);
-			ActivityPub::transmit($content, $contact['notify'], $owner['uid']);
+			ActivityPub::transmit($data, $contact['notify'], $owner['uid']);
 //			ActivityPub::sendFollowup($target_item, $owner, $contact, $public_message);
 			return;
 		} elseif ($target_item['uri'] !== $target_item['parent-uri']) {
 			// we are the relay - send comments, likes and relayable_retractions to our conversants
 			logger('ActivityPub relay: ' . $loc);
 			$data = ActivityPub::createActivityFromItem($target_item['id']);
-			$content = json_encode($data);
-			ActivityPub::transmit($content, $contact['notify'], $owner['uid']);
+			ActivityPub::transmit($data, $contact['notify'], $owner['uid']);
 //			ActivityPub::sendRelay($target_item, $owner, $contact, $public_message);
 			return;
 		} elseif ($top_level && !$walltowall) {
 			// currently no workable solution for sending walltowall
 			logger('ActivityPub status: ' . $loc);
 			$data = ActivityPub::createActivityFromItem($target_item['id']);
-			$content = json_encode($data);
-			ActivityPub::transmit($content, $contact['notify'], $owner['uid']);
+			ActivityPub::transmit($data, $contact['notify'], $owner['uid']);
 //			ActivityPub::sendStatus($target_item, $owner, $contact, $public_message);
 			return;
 		}